bg-image($url)
  background-image:url($url + "@2x.png")
  @media(-webkit-min-device-pixel-ratio:3),(min-device-pixel-ratio:3)
    background-image:url($url + "@3x.png")
border-1px-bottom($color)
  position: relative
  &:after
    display: block
    position: absolute
    left: 0
    bottom: 0
    width: 100%
    border-top: 1px solid $color
    content: ' '
border-1px-top($color)
  position: relative
  &:after
    display: block
    position: absolute
    left: 0
    top: 0
    width: 100%
    border-top: 1px solid $color
    content: ' '
border-1px-left($color)
  position: relative
  &:after
    display: block
    position: absolute
    left: 0
    top: 0
    height: 100%
    border-left: 1px solid $color
    content: ' '
border-1px-right($color)
  position: relative
  &:after
    display: block
    position: absolute
    right: 0
    top: 0
    height: 100%
    border-right: 1px solid $color
    content: ' '


